# US 7,608,172 B2 · High-purity ferromagnetic sputter targets and method of manufacture

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- Number: US 7,608,172 B2
- Document ID: US7608172B2
- Status: Granted
- Kind: B2
- Application number: 10/637,531
- Filed: 2003-08-11
- Published: 2004-02-19
- Granted: 2009-10-27
- Earliest claimed: 2002-05-31
- Assignees: Praxair S.T. Technology, Inc.
- Inventors: Andrew C. Perry; Holger J. Koenigsmann; David E. Dombrowski; Thomas J. Hunt
- Web page: https://patentgrep.com/patent/US7608172B2

## CPC

- C23C 14/3414: {Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy}
- C22F 1/10: of nickel or cobalt or alloys based thereon
- H01F 41/183: {Sputtering targets therefor}
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

The method manufactures high-purity ferromagnetic sputter targets by cryogenic working the sputter target blank at a temperature below at least −50° C. to impart at least about 5 percent strain into the sputter target blank to increase PTF uniformity of the target blank. The sputter target blank is a nonferrous metal selected from the group consisting of cobalt and nickel; and the nonferrous metal has a purity of at least about 99.99 weight percent. Finally, fabricating the sputter target blank forms a sputter target having an improved PTF uniformity arising from the cryogenic working.

## Claims

### Claim 1

A high-purity nonferrous sputter target, the nonferrous sputter target having a sputter source selected from the group consisting of cobalt, the sputter source having a top surface for sputtering metal atoms onto a substrate, a side edge, a purity of at least about 99.99 weight percent, a single phase crystallographic structure, and a uniform PTF, the PTF uniformity being less than about 3.5 percent of the average PTF for the formula:
PTF
⁢
⁢
uniformity
=
n
⁢
∑
x
2
-
(
∑
x
)
2
n
⁡
(
n
-
1
)
where n is the number of measurements at different locations, n is at least 8, and x is the PTF measurement at each location 5 cm from the side edge, wherein the nonferrous metal sputter target deposits a film having a sheet resistance Rs uniformity of less than 1.0 percent.

### Claim 2 (depends on 1)

The sputter target of claim 1 wherein the metal sputter source is cobalt having a permeability between about 4 and 8 as measured parallel to the top surface of the metal sputter source and a permeability between about 9 and 12 as measured perpendicular to the top target surface of the metal sputter source.

### Claim 3 (depends on 1)

The sputter target of claim 1 wherein the metal sputter source is cobalt and the PTF uniformity is less than about 3 percent of the average PTF.